Picking numbers within a list with an interval of 60You might need to explain a bit more clearly. For example, what's wrong with {5, 14} as one of your sublists? Posting your existing code always helps too. Split and Gather are useful functions for this type of problem.

Efficient Generation of Subgraphs (or, unfriend a friend a day)With 10 people, they each have a choice of 9 unfriendings, giving $9^{10}$ possibilities. The next day there is probably still 10 people with 8 choices, so the total possibilities so far is $9^{10} 8^{10}$. This gets very big, very fast. I don't think you are going to brute force it.

Determine the Number of Lines in a Text FileAs written, the code is reading char by char. Who knows if the underlying implementation is reading in more efficient chunks? I agree that C++ I/O is a bit disappointing (and not the easiest to use either!). I might go buy a solid state drive to compensate.

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